在运行时指定具有开放泛型和类型的Autofac

问题描述

文档指出Autofac支持开放式泛型，并且我能够在基本情况下进行注册和解析，如下所示:

The documentation states that Autofac supports open generics and I am able to register and resolve in a basic case like so:

注册:

builder.RegisterGeneric(typeof(PassThroughFlattener<>))
       .As(typeof(IFlattener<>))
       .ContainerScoped();

解决:

var flattener = _container.Resolve<IFlattener<Address>>();

上面的代码可以正常工作.但是，假设在运行时之前我不知道提供给IFlattener的类型，我想做这样的事情:

The above code works just fine. However, assuming that I will not know the type provided to IFlattener until runtime, I want to do something like this:

object input = new Address();
var flattener = (IFlattener)_container.Resolve(typeof(IFlattener<>), new TypedParameter(typeof(IFlattener<>), input.GetType()));

使用AutoFac可以吗?我是从以下使用StructureMap的想法中得到的:

Is this possible with AutoFac? I got the idea from the following using StructureMap:

http://structuremap.sourceforge.net/Generics.htm

我正在努力实现本文概述的相同目标.

I'm trying to achieve the same goal outlined in this article.

推荐答案

使用Autofac当然可以实现.在注册时间"，这基本上就是您要做的:

This is certainly possible with Autofac. At "register time", this is what you basically do:

1. 注册打开的通用类型(PassThroughFlattener<>)
2. 注册任何特定类型(AddressFlattener)
3. 注册一个可用于基于输入对象解析IFlattener的方法

在解决时间"，您将执行以下操作:

At "resolve time", you will do:

1. 解决方法
2. 使用输入参数调用方法以解决IFlattener实现

这是一个(希望)工作的示例:

Here's a (hopefully) working sample:

var openType = typeof(IFlattener<>);

var builder = new ContainerBuilder();
builder.RegisterGeneric(typeof(PassThroughFlattener<>)).As(openType);
builder.Register<AddressFlattener>().As<IFlattener<Address>>();
builder.Register<Func<object, IFlattener>>(context => theObject =>
    {
        var closedType =
            openType.MakeGenericType(theObject.GetType());
            return (IFlattener) context.Resolve(closedType,
                new PositionalParameter(0, theObject));
    });
var c = builder.Build();

var factory = c.Resolve<Func<object, IFlattener>>();

var address = new Address();
var addressService = factory(address);

Assert.That(addressService, Is.InstanceOfType(typeof(AddressFlattener)));

var anything = "any other data";
var anyService = factory(anything);

Assert.That(anyService, Is.InstanceOfType(typeof(PassThroughFlattener<string>)));

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